The Trade Unit Values Database
_____________
Antoine Berthou & Charlotte Emlinger
DOC UM E NT DE T R A V A I L
No 2011 – 10
April
CEPII, WP No 2011-10
The Trade Unit Values Database
T ABL E
OF C ONT E NT S
Non-technical summary ....................................................................................................... 3
Abstract ............................................................................................................................... 4
Résumé non technique ......................................................................................................... 5
Résumé court....................................................................................................................... 6
Introduction ......................................................................................................................... 7
1.
Description of the raw Tariff lines Data ........................................................................ 9
1.1. Nomenclature and level of disaggregation ........................................................... 9
1.2. Reporting threshold ............................................................................................11
1.3. Quantity units and missing quantity ....................................................................11
2.
The processing methodology of the Trade Unit Values database ..................................12
2.1. Subtotals and reporting thresholds ......................................................................12
2.2. Conversion of quantities into weights .................................................................13
2.3. Outliers detection and treatment .........................................................................13
2.4. Missing quantities ...............................................................................................13
2.5. Aggregation ........................................................................................................14
3.
The Trade Unit Values database ..................................................................................14
3.1. Description of the files........................................................................................14
3.2. Trade coverage of the database ...........................................................................15
4.
Validation tests of the Trade Unit Values database .......................................................16
4.1. Methodological differences with Comtrade.........................................................16
4.2. Dispersion of unit values ....................................................................................18
4.3. Econometric analysis ..........................................................................................21
Conclusion .........................................................................................................................24
Bibliography.......................................................................................................................25
Appendix ............................................................................................................................26
A1. Country coverage in the Trade Unit Value database ..............................................26
A2. Summary of the quantity correction in Comtrade ..................................................28
List of working papers released by CEPII ...........................................................................30
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The Trade Unit Values Database
T H E T R ADE U NI T V AL UE S D AT AB A SE
N ON - T E C H NI C A L
SUM M AR Y
Unit values are an essential tool in the toolbox of empirical trade and macro economists. They
are used to approximate trade “prices”, which are not available for a large number of
countries, items and years. Trade unit values, however, can be computed as the ratio of values
and quantities using international trade datasets with product disaggregation. As their primary
objective is to provide information about “trade”, using these data to calculate trade unit
values may be awkward. In particular, estimation of missing quantity information in
worldwide trade dataset (aimed at improving countries coverage) reduces the reliability of
unit values as a proxy for trade prices.
This paper presents a new, worldwide database, the Trade Unit Values dataset. Our
methodology relies on the “Tariff lines” database of the United Nations Statistical Division,
corresponding to the values and quantities of trade declared by individual countries to the UN.
These data are processed in order to provide reliable and comparable unit values across
countries. Unit values are computed for each reporter (which can be an exporter or importer),
partner and product at the highest level of disaggregation reported in the Tariff lines database.
This requires that all quantity units are converted into weights. Extreme unit values are
detected using the cross-sectional and time dimensions of the data. Finally, unit values are
aggregated at the HS 6-digits level, allowing international comparisons.
Overall, this strategy improves the reliability of unit values. We show that the Trade Unit
Values database exhibits a higher dispersion of trade prices by product category, as compared
to the UN Comtrade. Econometric estimations show that this higher dispersion is well
explained by economic aggregates. The data can therefore be an interesting tool for
performing international comparisons in terms of vertical specialization among product
categories, or for analyzing the relation between macroeconomic aggregates and the pricing
strategy of countries.
The final Trade Unit Values database contains Unit Value information (in US dollars per ton)
over the period 2000-2008, with 173 reporters, 255 partners, and more than 5,000 product
categories per year. The coverage changes over time. Unit values are ultimately provided in
Harmonized System 1996 and 2002 revisions with 6 digits, Free on Board (FOB) and Cost of
Insurance and Freight (CIF). The CIF unit values rely on importers’ declarations, and include
all trade costs (except tariffs and domestic taxes after the border). The FOB unit value is a
proxy for the trade price at the factory gate, relying on exporters’ declarations, and does not
include trade costs.
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The Trade Unit Values Database
A B ST R A C T
Trade unit values are commonly used as proxies for trade prices in empirical research in
international economics. Existing datasets providing international trade unit values for a large
number of countries typically suffer from a number of statistical biases, due to the
aggregation of unit values and the harmonization of quantity information. These biases reduce
the reliability of unit values as a proxy for trade prices. This paper presents the Trade Unit
Values dataset, a new database developed to circumvent these statistical issues. Bilateral trade
unit values are computed at a very high level of disaggregation before aggregation into
Harmonized-System 6-digits categories to allow for cross-country comparability. Our
processing strategy improves the differentiation of trade prices within product categories, as
compared to existing worldwide datasets. A simple econometric analysis shows that unit
values in our database are well explained by economic aggregates.
JEL Classification: E3; F1; F4
Key Words:
Unit value, trade price, international trade
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The Trade Unit Values Database
U NE
R É SUM É
B A SE DE DONNÉ E S DE V A L E UR S UNI T AI R E S
NON T E C HNI QUE
L’analyse empirique de la spécialisation en gamme des pays exportateurs, de leur stratégie de
prix ou des termes de l’échange nécessite de disposer de données de prix du commerce fiables
et désagrégées. Les valeurs unitaires, qui correspondent au ratio des valeurs et des quantités
du commerce sont généralement utilisés comme proxy de ces prix. Les bases de données de
valeurs unitaires existantes présentes certaines limites. Beaucoup d’entre elles ne couvrent
qu’un nombre restreint de pays. Dans le cas des bases internationales comme Comtrade, le
traitement des quantités manquantes, visant à améliorer la couverture de la base, limite
fortement la fiabilité des données quand il s’agit de calculer les valeurs unitaires.
Ce papier présente la nouvelle base de données Trade Unit Value du CEPII, qui a pour
objectif de fournir des données de valeurs unitaires fiables et désagrégées pour la plupart des
pays du monde. Cette base propose les valeurs unitaires du commerce en dollar par tonne
pour 173 déclarants, 255 partenaires et plus de 5000 produits. Elle couvre actuellement la
période 2000 à 2008. Les valeurs unitaires sont proposées dans deux révisions du système
harmonisé (1996 et 2002) à 6 digits, en Coût Assurance Fret (CAF) ou Free on Board (FOB).
Les données CAF sont issues des déclarations des importateurs et incluent tous les coûts au
commerce à l’exception des droits de douane. Les valeurs unitaires FOB sont calculées à
partir des déclarations des exportateurs et n’incluent ni coûts de transport ni assurances.
Les valeurs unitaires de la base Trade Unit Value sont calculées à partir de données de
commerce en valeur et quantité fournies par la Division Statistique des Nations Unies. Ces
données correspondent aux déclarations brutes des pays au Nations Unies et sont à un niveau
de désagrégation des produits extrêmement fin, propre à chaque déclarant. Ces données ont
été traitées afin de fournir des valeurs unitaires comparables entre pays et dans le temps. Dans
un premier temps, les quantités, qui sont déclarées dans différentes unités, ont été converties
en tonnes. Les valeurs extrêmes, issues d’erreurs de mesure ou de différents seuils de
déclaration sont ensuite retirées de la base. Enfin, les valeurs unitaires sont agrégées au niveau
6 digit de la nomenclature harmonisée.
Les valeurs unitaires de la base Trade Unit Value présentent une plus forte dispersion par
catégorie de produit que valeurs unitaires qui peuvent être calculées à partir de la base de
données Comtrade des Nations Unies. L’estimation d’une équation de gravité standard montre
que cette plus forte dispersion s’explique par les agrégats économiques. La base de données
Trade Unit Value constitue un outil intéressant pour les analyses empiriques que ce soit de la
discrimination prix des pays exportateurs en fonction de leurs marchés de destination ou de la
spécialisation verticale des pays par catégorie de produits.
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CEPII, WP No 2011-10
R É SUM É
The Trade Unit Values Database
C OUR T
L’analyse empirique du commerce international utilise généralement les valeurs unitaires
comme proxy des prix du commerce. L’agrégation des valeurs unitaires et l’harmonisation
des données de commerce en quantité limitent fortement la fiabilité des bases de données
internationales de valeurs unitaires existantes. Ce papier présente la nouvelle base de données
Trade Unit Value développée par le CEPII pour réduire ces biais statistiques. Les valeurs
unitaires qu’elle propose ont été calculées à un niveau fin de la nomenclature des produits
avant d’être agrégées au niveau 6 digits de la nomenclature harmonisée. Le traitement réalisé
permet d’accroître la dispersion des prix du commerce à l’intérieur des catégories de produits,
comparativement aux bases de données existantes. L’estimation d’une équation de gravité
standard montre que cette plus forte dispersion s’explique par les agrégats économiques.
Classification JEL : E3, F1, F4
Mots-clefs :
Valeur unitaire, prix du commerce, commerce international
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The Trade Unit Values Database
T H E T R ADE U NI T V AL UE S D AT AB A SE 1
Antoine Berthou and Charlotte Emlinger
*
I NT R ODUC T I ON
Trade prices are an essential tool to empirical research in international economics. They are
used in a macroeconomic perspective to compute trade price indexes (Broda and Weinstein,
2006) and terms of trade, or to identify countries’ specialization along a ladder of vertically
differentiated varieties (Schott, 2008; Fontagné et al. 2008). Improvements of trade price data
can take the form of a better coverage in terms of countries, the degree of disaggregation for
which prices are available (goods, firms), and the reliability of the reported information.
Researchers usually have to arbitrate between two types of datasets. Firm-level datasets
typically provide the unit value of one goods category sold on a market, by a firm, over a
certain period of time. These data are, however, available for a limited number of countries
2
with restricted access. Datasets such as the United Nations Comtrade database, or the
3
Eurostat Comext, offer a larger coverage in terms of countries, but loose the firm dimension.
In all cases, trade “prices” are usually not available. Statistical institutes or researchers usually
compute “unit values”, which simply correspond to the ratio of the value and the quantity of
shipments. The reliability of value and quantity is therefore directly affecting the
approximation of “trade prices” with unit values. In the case of datasets covering trade flows
among a large number of countries, harmonization is required to make national datasets as
much comparable as possible. This processing, though improving the coverage and
comparability of data, can be detrimental to the reliability of unit values as a proxy for trade
prices.
This paper presents a new, worldwide database, the Trade Unit Values dataset. Our
methodology relies on the “Tariff lines” database of the United Nations Statistical Division,
corresponding to the values and quantities of trade declared by individual countries to the UN.
These data are processed in order to provide reliable and comparable unit values across
countries. Unit values are computed for each reporter (which can be an exporter or importer),
1
We acknowledge financial support from AgFoodTrade. We thank Matthieu Crozet, Houssein Guimbard, Alix de
Saint Vaulry and Lionel Fontagné for comments and suggestions. We are grateful to the United Nations Statistical
Division for providing the tariff lines trade data, and for their helpful assistance.
*
CEPII, 113 rue de Grenelle, 75007 Paris. Contact: antoine.berthou@cepii.fr and charlotte.emlinger@cepii.fr.
2
See Bastos and Silva (2008) for Portugal; Manova and Zhang (2009) for China, Martin (2010) for France or Görg et
al., (2010) for Hungary.
3
For instance, Campa and Goldberg (2005) use Comext data to analyse the exchange rate pass-through in eurozone
countries. Chang and Winters (2002) analyse the effect of regional agreements on import prices using UN
COMTRADE.
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The Trade Unit Values Database
partner and product at the highest level of disaggregation reported in the Tariff lines database.
This requires that all quantity units are converted into weights. Extreme unit values are
detected using the cross-sectional and time dimensions of the data. Finally, unit values are
aggregated at the HS 6-digits level, allowing international comparisons.
Our processing methodology aims at improving the reliability of unit values, as compared to
existing unit values in trade datasets with World coverage such as the UN Comtrade. First, the
processing that is implemented to develop the UN Comtrade dataset generates a complete
dataset without missing quantity, when the value is available. Missing quantities are
estimated, notably using a unique standard unit value defined at the World level. When such
estimation is implemented, this removes all the difference in prices across countries.
Conversely, the Trade Unit Values database does not rely on a World unit value to estimate
quantity information, which enables to keep heterogeneity in terms of pricing across
countries. Second, Comtrade aggregates separately values and quantities into HS 6-digits
nomenclature. This can bias unit values when some of the quantity information is initially
missing at a higher level of disaggregation. In our database, unit values, rather than the values
themselves are computed at the highest level of disaggregation before aggregation in HS 6digits categories, thus reducing the bias due to separate aggregation of values and quantities.
Overall, this strategy is expected to provide a smaller coverage of unit values as compared
with Comtrade, but improve the reliability of unit values. We show that the Trade Unit Values
database exhibits a higher dispersion of trade prices by product category, as compared to the
UN Comtrade. Econometric estimations show, however, that this higher dispersion is well
explained by economic aggregates. The data can therefore be an interesting tool for
performing international comparisons in terms of vertical specialization among product
categories, or for analyzing the relation between macroeconomic aggregates and the pricing
strategy of countries.
The final Trade Unit Values database contains Unit Value information (in US dollars per ton)
for the period 2000-2008 with a maximum of 173 reporters, 255 partners, and more than
5,000 product categories per year. Coverage improves over time. Unit values are ultimately
provided in Harmonized System 1996 and 2002 revisions with 6 digits, Free on Board (FOB)
and Cost of Insurance and Freight (CIF). The CIF unit values rely on importers’ declarations,
and include all trade costs (except tariffs and domestic taxes after the border). The FOB unit
value is a proxy for the trade price at the factory gate, relying on exporters’ declarations, and
does not include trade costs.
This paper starts with a presentation of the raw tariff lines data that are used to construct the
unit values dataset. The second section describes the processing methodology that is used to
construct HS 6-digits unit values. Section 3 presents the different files composing the
database. Section 4 compares the Unit Values and Comtrade databases. Finally, Section 5
concludes.
8
CEPII, WP No 2011-10
1.
D E SC R I PT I ON OF
The Trade Unit Values Database
T H E R AW
T AR IFF
L I NE S
D AT A
The Unit Value Database developed by the CEPII relies on Tariff lines data, provided by the
United Nation Statistical Division. These data provide raw information on trade value and
quantity as reported by the declaring country, for 173 reporters and 255 partner countries.
Each country declares both imports (CIF) and exports (FOB).
Despite UN Statistical Division’s recommendations to the declaring countries, a high
heterogeneity remains in countries’ declarations. Nomenclature of commodity codes,
reporting thresholds and quantity units can differ across countries. Raw data also include
subtotals and several flows can be associated with a given exporter, importer, product, and
year (flows are duplicated). Considerable cleaning is therefore required before the
construction of the dataset. In this section, we provide a description of the raw tariff line data.
1.1. Nomenclatur e and level of disaggr egation
The Harmonized System nomenclature with 6-digit product codes is commonly used for
reporting trade flows (both exports and imports) by most countries in the World. Countries
also often add one or more digits to HS product code. While this improves the detail in the
nature of the products traded, this removes the comparability of trade flows across countries.
Table 1 illustrates in how additional detail in the product nomenclature is materialized into
products, with the example of wind musical instruments in the US classification. 6-digit
categories can obviously contain products which are highly different by nature.
Table 1. Wind musical instruments in the US product classification
6-digits
US Product code
8-digits
10-digits
Product label
Wind
instruments
other
brasswind
Bagpipes
Other woodwind instruments
Clarinets
Saxophones
Flutes
920590
920590 20
920590 40
920590 40 20
920590 40 40
920590 40 60
than
Sources: US Census Bureau.
The average level of disaggregation by country in the database corresponds to the 8-digit
level, but some countries, like Turkey, use a very detailed country code system (Table 2
below). A few countries, like Aruba or Bermuda, declare using commodity code of 4 digits.
In this case, trade flows do not match to the 6-digit HS nomenclature and cannot be compared
with other countries’ flows. Though, more digits do not necessarily mean that more products
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The Trade Unit Values Database
are available in the country classification. For example, Turkey reports more digits in product
codes in comparison to Canada, but has fewer products.
Table 2. Level of disaggregation and number of commodity codes by country in the
tariff line database (Import CIF database 2007).
Number of Digits
Number of products
Mean
8
5,920
Median
8
5,327
Maximum
12 (Turkey)
18,250 (Canada)
Minimum
4 (Aruba)
303 (Aruba)
Source: Tariff line Database, United Nations Statistical Division
The Harmonized System nomenclature was revised several times since its introduction in
1988. Each revision differs from the previous one by distinguishing new products or
aggregating others. At a higher level of disaggregation, the frequency of revisions is even
higher. Consequently, the Tariff line database has several revisions (rev0, rev1, rev2 and
rev3) of the HS for a given year (table 3). For example, in 2007, the majority of countries
(109) declared in the revision 3 of the HS, which corresponds to 93.23% of trade but 36
countries still declared in revision 1. Up to 3 countries did not declare in a HS revision but in
SITC.
Table 3. Share in world trade (number of countries) by revision of the Harmonized
System in the tariff line database
H0
H1
H2
H3
2008 0.01
(3)
0.73 (10) 6.03 (32) 93.23 (109)
2007 0.18
(7)
0.91 (13) 10.64 (65) 88.27 (77)
2006 0.18
(7)
1.18 (19) 98.62 (142)
.
.
2005 0.17
(7)
1.55 (23) 98.25 (139)
.
.
2004 0.18 (10)
1.82 (26) 97.97 (98)
.
.
2003 0.19
(8)
2.32 (30) 97.41 (71)
.
.
2002 0.17
(8)
4.39 (36) 95.20 (51)
.
.
2001 0.40
(10 99.24 (74)
.
.
.
.
2000 0.33 (10) 99.38 (66)
.
.
.
.
Source: Tariff line Database, United Nations Statistical Division
10
S3
.
.
0.02
0.02
0.03
0.08
0.24
0.35
0.30
.
.
(1)
(1)
(1)
(2)
(3)
(3)
(2)
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The Trade Unit Values Database
1.2. R eporting threshold
Trade values at the tariff line level are converted into dollars by the UN Statistical Division.
The reporting threshold generally depends on the national currency and thus varies from one
country to another. Having different minimum thresholds reduces the comparability across
countries, since a given flow may appear or not in the dataset according to national practices.
Table 4 reports the statistics concerning this threshold. The reporting threshold is low with a
median of one dollar. Declarations with values equal to zero are observed in the database for
Rwanda or Poland.
Table 4. Reporting threshold in the tariff lines database (dollars)
reporting threshold
Mean
83
Median
1
Maximum
37,830 (Syrian Arab Republic)
Minimum
0
Source: Tariff line Database, United Nations Statistical Division
1.3. Quantity units and missing quantity
Declaring countries use different quantity units according to the products. Eight
differentquantity units are observed in the Tariff line database: kilograms, meters, squared
meters, thousand of kilowatt-hour, units, pairs, thousands of units. Declarations in kilograms
correspond to almost 60% of the total value of trade in the database for 2007 (Table 5). A
high heterogeneity is observed across countries concerning the quantity units. Germany, for
example, declares almost all its trade in kilograms, but only 19.5% of the US imports are
declared in this unit.
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Table 5. Quantity units by country, share of trade in value (CIF data in 2007).
no quantity
m²
1000 kWh
m
units
pairs
liters
kg
thousand
units
4.76
0.66
0
0.03
18.87
0.04
0.06
75.58
United
Kingdo
m
3.37
1
0.07
0.02
32.42
0.92
6.87
55.23
21.83
0.72
0.12
0.09
40.7
0.93
15.93
19.53
0
0.1
0.15
World
Brazil
China
France
Germany
Italy
India
8.9
0.68
0.21
0.14
25.98
0.56
3.47
59.37
13.56
0.36
0.03
0.02
35.29
0.25
0.23
50.26
1.29
0.1
0.02
0.88
40.16
0.05
0.09
57.4
3.01
1.01
0.12
0.04
28.9
0.96
0.54
65.09
0.43
0
0
0
0
0
0
99.57
5.24
1.1
0.52
0.04
28.58
0.92
0.35
62.75
0.69
0
0.01
0.33
0
0.5
USA
Source: Tariff line Database, United Nations Statistical Division.
2.
T HE
PR OC E SSI NG M E T HODOL OG Y OF T H E
T R A DE U NI T V AL UE S DA T A B A SE
The Trade Unit Value database is constructed by processing the raw tariff lines data. The
objective is to provide a World-level dataset reporting reliable unit values at a high level of
disaggregation. The above description of the tariff line data has illustrated some issues that
have to be solved in the raw data to compute reliable unit values. This section describes the
processing methodology we used to construct the Trade Unit Value database.
2.1. Subtotals and reporting thresholds
The first step in our data processing consists in removing totals, subtotals and zero trade flows
when they appear in the data. Trade flows reported using a nomenclature that is not
compatible with the Harmonized System classification are also dropped.
As already mentioned, one important issue in the data is related to the existence of different
reporting thresholds among reporters. Different reporting thresholds can indeed introduce
some heterogeneity among reporters due to a statistical bias. To deal with this statistical issue,
we impose a USD 1,000 reporting threshold on trade flows when they are aggregated into HS
6-digits categories (as in the Comtrade dataset). At the level of commodity codes, a second
reporting threshold is set to USD 10.
Values and quantities of duplicates (same reporter, partner, commodity code, year) are
aggregated in order to keep only one value and quantity for a given flow.
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The Trade Unit Values Database
2.2. C onver sion of quantities into weights
Conversion factors are computed using UN Comtrade mirror flows (i.e. the quantity declared
by the exporter is compared with the quantity declared by the importer). When quantities are
declared in different units by the exporter and the importer, this provides an empirical
conversion factor. A single conversion factor is computed by HS6 product code at the World
4
level, on the basis of mirror flows.
2.3. Outliers detection and treatment
Our procedure to detect outliers takes advantage of the distribution of unit values in the cross
section, and the evolution of unit values over time. First, a median unit value is computed by
reporter, commodity code, and year. Outliers are identified if a unit value exceeds the
median*100 or is below the median/100. Second, the time dimension in the data is used at the
HS-6 digits level to compare the evolution of unit values over time, for a given reporterpartner-product combination. Our condition implies that a single unit value at time t cannot be
a thousand times higher than the unit value of the same flow at time t-1 or t+1. When outliers
are identified, the observation is dropped from the data so as to keep only reliable unit value
information.
2.4. M issing quantities
As discussed in the introduction, our objective is to provide a database of unit values that
improves the comparability and the reliability of each observation. This, however, tends to
reduce the coverage: for many countries, the value of a trade flow is not associated with the
corresponding weight in a large proportion of cases. In section 2.2, we showed how empirical
conversion factors have been used to convert all quantities into weights. Hence, when
quantity is available in any quantity unit, we are able to compute a trade unit value in terms of
US dollars per ton.
When some value is declared but the quantity is missing, no unit value is a priori available. In
this situation, several cases apply. If the reporter never reports any quantity information for
the same commodity code, we leave the unit value as “missing”. In the case where the
quantity is missing for one flow, but is reported for the same commodity and reporter but
different partners, the missing unit value is replaced by the average unit value weighted by the
value of trade flows. For example, France may report the exported value and quantity of a
certain category of cars, for all destinations but one. In this case, we compute the average unit
value corresponding to exports of the sale category of cars by France. The missing unit value
is then replaced by the average unit value. In using this strategy, we assume that the unit value
is the same over all partners for a given commodity code, when information is missing.
However, we do not impose that several reporters share the same unit value.
4
A similar methodology is implemented to construct the BACI data. See Gaulier and Zignago (2010).
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The Trade Unit Values Database
2.5. A ggregation
All the steps that were discussed in the previous paragraphs describe how the raw tariff lines
data are used to compute reliable unit values at the level of commodity codes. As discussed in
the presentation of the raw data, in Section 1, most countries report international trade flows
to the United Nations using their own product nomenclature. National nomenclatures
generally correspond to the Harmonized System nomenclature augmented with additional
digits that are specific to each country. Cross-country comparability therefore requires that all
unit values are aggregated into the same HS 6-digits revision.
The HS-6 digits unit value is obtained, for each reporter and partner, by taking the average
unit value over all commodity codes weighted by the quantity of each flow. This aggregation
strategy relies on unit values information rather than on separate values and quantities. This
allows keeping information of a better quality for HS 6-digits unit values, especially when
quantities in weight are missing at the disaggregated level.
Different revisions of the Harmonized System nomenclature are used in the tariff line
database. In order to allow comparison across countries and years, HS 6-digits level
commodity code are converted into two different revisions, revision 1 (HS96) and revision 2
(HS2002), using correspondence tables from the UNSD. Export and Import data are separated
in order to provide two different databases.
3.
T H E T R ADE U NI T V AL UE S DA T A B A SE
3.1. Description of the files
The unit value database provides import (Cost Insurance Fret) and export (Free On Board)
unit values using the Harmonized System of classifications with revisions 1996 and 2002.
This results into four databases, each database being decomposed into 9 files corresponding to
the years covered by the data (2000-2008).
Each file is coded using the following name: “UV_rev_rg_yr.csv” with rev the HS revision
(“96” or “02”); rg the declaration regime (“x” for exporter, “m” for importer); yr the year
(2000 to 2008).
The 5 variables specified in each file are:
-
“i” the exporter;
“j” the importer;
“Hs6_rev” the hs6 code followed by the HS revision (“96” or “02”);
“Yr” the year;
“uv” the unit value in US dollars per ton;
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The Trade Unit Values Database
Table 6 below provides a brief description of the number of observations, reporters, partners,
products and years in each of the four databases.
Table 6. Summary description of the four Trade Unit Values databases
HS96
-Number of observations: 35,221,995
-Number of reporters: 173
CIF data -Number of partners: 255
-Number of products: 5,113
-Number of years: 9
-Number of observations: 33,653,044
-Number of reporters: 173
FOB data -Number of partners: 255
-Number of products: 5,113
-Number of years: 9
Source: Trade Unit Value Database - CEPII
HS02
-Number of observations: 34,922,652
-Number of reporters: 173
-Number of partners: 255
-Number of products: 5,224
-Number of years: 9
-Number of observations: 33,332,222
-Number of reporters: 176
-Number of partners: 255
-Number of products: 5,224
-Number of years: 9
The United Nations Statistical Division does not provide tariff line data for all countries since
2000. The number of reporters depends on the year (Table 7). The database covers the
majority of countries since 2005 (more than 150). Table A1 in annex provides the time
coverage of each country in the database.
Table 7. Summary description of the CIF import HS96 Trade Unit Values database
observations reporters partners
2008
5 621 584
145
252
2007
5 611 642
152
252
2006
5 143 860
156
251
2005
4 990 446
157
253
2004
3 767 429
119
254
2003
3 047 800
99
252
2002
2 607 517
85
251
2001
2 266 510
75
250
2000
2 165 207
71
249
Source: Trade Unit Value Database – CEPII
products
5113
5113
5113
5113
5113
5113
5113
5113
5113
3.2. T rade coverage of the database
Despite our treatment of missing unit value in the database, there is still a large share of
missing unit value. Table 8 below presents the coverage of our database, in proportion of the
15
CEPII, WP No 2011-10
The Trade Unit Values Database
number of trade flows in the UN Comtrade database. The UN Comtrade provides values for
all trade flows at the 6 digit level of the HS. Comparing the number of flows of the two
databases gives the coverage of the Unit Value database relative to all existing trade flows.
At the World level, unit values are available for, on average, 56% of the import trade flows.
The coverage of the base is lower in the first years (44% for 2000) than for the last one (82%
for 2008). The low number of reporters in the raw data for the early years explains this
difference of coverage. Some heterogeneity can be observed across countries. For countries
like the United States or China, unit values are observed for a small proportion of flows
(respectively 56% and 57%) whereas these countries are in the database for the entire period.
Table 8. Coverage of the CIF import HS96 Trade Unit Values database compared to the
UNSD Comtrade database
% of flows % of trade values
2008
82%
79%
2007
82%
79%
2006
75%
78%
2005
74%
80%
2004
64%
69%
2003
54%
64%
2002
48%
62%
2001
43%
57%
2000
44%
55%
Source: Trade Unit Value Database - CEPII
4.
V A L I DAT I ON T E ST S OF T HE T R ADE U NI T V A L UE S DA T A B A SE
The objective of the Trade Unit Values database, as discussed in introduction, is to improve
the reliability of trade prices that are used in a number of empirical investigations. In order to
assess whether we reach this objective, we need a reference dataset. In this exercise, we
choose the unit values computed from the UN Comtrade dataset as a counterfactual. The UN
Comtrade is the closest dataset in terms of country and product coverage; it also uses the same
raw data.
4.1. M ethodological differ ences with C omtrade
The procedure that is implemented to construct the Trade Unit Values database differs from
the UN Statistical Division processing methodology for the construction of Comtrade.
16
CEPII, WP No 2011-10
The Trade Unit Values Database
Differences arise with respect to the aggregation strategy, the conversion of quantities into
5
weights, the identification of outliers, and the treatment of outliers and missing weights.
In the Comtrade dataset, values and quantities are aggregated into the HS 6-digits
nomenclature separately, before unit values are computed. This procedure may bias unit value
when some quantities are missing at a higher level of disaggregation (e.g. missing quantity
increases unit value after aggregation). In our processing, unit values are computed at the
highest level of the disaggregation and then aggregated in HS 6-digits categories, which
reduces this bias.
When weights are missing but other quantity units are available, weights can be estimated
using conversion factors provided by the declaring country or the Food and Agriculture
Organization (FAO). As discussed in section 2, our strategy uses conversion factors computed
using UN Comtrade flows, and allows a conversion in most of cases.
When outliers or missing weights are detected, UN Comtrade quantities are estimated using
the mean unit value that is recorded for the same reporter and product category. This requires
that both quantity and value information are recorded for the same exporter and product, but
for a different destination. Our procedure is similar, but is implemented at the highest level of
disaggregation of commodity code. When this estimation is not possible, a Standard Unit
Value is computed at the World level, and combined with declared values to estimate quantity
information. The Standard Unit Value assumes that all countries share the same price for a
given HS 6-digits product category. This processing allows to estimate all missing quantities,
but potentially reduces the variance of unit values observed for a given product on a given
market.
Table 9 below reports for the years 2000 to 2008 the share of estimated and non-estimated
quantity information in the Comtrade data, using the “flag” information that can be
downloaded together with the dataset. The table shows that around 20% of observations are
associated with estimated quantity information (quantity unit, net weight, or both). Estimated
quantities may represent a higher share of flows in some countries, like USA (33%), where
few quantities are declared in weight. For other countries like UK, only 4% of the flows have
estimated quantities in the Comtrade dataset. Most importantly, according to the UN
Statistical Division, about 60% of estimated quantities are obtained using the Standard Unit
6
Value by product category as a reference. In that case, estimated unit values do not match
country characteristics such as their unit production cost or the specialization of production
along the quality ladder. This implies that empirical investigations that rely partially on
estimated quantity information may suffer from important biases in the analysis.
5
6
Appendix section A1 provides a full description of the different steps of the Comtrade methodology.
See UNSD report (2009)
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CEPII, WP No 2011-10
The Trade Unit Values Database
Table 9. Share of estimated and non-estimated quantity information in Comtrade
No estimation
(flag = 0)
2008
79%
2007
80%
2006
72%
2005
69%
2004
76%
2003
77%
2002
79%
2001
79%
2000
80%
Source: UN Comtrade
Quantity unit
estimated
(flag = 2)
Net weight
estimated
(flag = 4)
5%
5%
9%
10%
8%
7%
6%
5%
5%
6%
7%
6%
4%
5%
4%
5%
4%
5%
Both quantity
unit and net
weight
estimated
(flag = 6)
9%
8%
12%
17%
12%
12%
10%
11%
10%
4.2. Dispersion of unit values
We now provide some empirical analysis regarding the dispersion of unit values in the Trade
Unit Values and Comtrade datasets. The objective is to show how Trade Unit Values differs
from existing datasets.
A simple correlation shows that the Trade Unit Values and Comtrade unit values are highly
correlated (88%). We then compute the kernel density of unit values extracted from both
datasets. Regarding the Comtrade dataset, we provide a density analysis using the full sample,
the sample where quantity is not estimated (flag = 0 or flag = 2), and the sample where
quantity is estimated (flag=4 or flag=6). The density associated with each dataset is presented
in Figure 1. The density of the Comtrade data with estimated quantity reports a sharper peak,
meaning that these data are more concentrated around the mean value. This can be explained
by the estimation of quantity information in Comtrade, which relies in many cases on a
Standard Unit Value by product category. This also explains why the full Comtrade dataset
also reports a sharper peak. When quantities are not estimated in Comtrade, the shape of the
density is similar as what is observed for the Trade Unit Values.
18
CEPII, WP No 2011-10
The Trade Unit Values Database
0
.1
Kernel density
.2
.3
.4
Figure 1. Kernel density of the logarithm of unit values in Trade Unit Values (TUV)
and Comtrade (CT) databases in 2007
10
0
-10
Density TUV
Density CT flag == 0 or 2
20
30
Density CT
Density CT flag == 4 or 6
Note: The density distribution is based on the log of unit values in each database. CT= Comtrade,
TUV= Trade Unit Value
Source: Author’s Calculations
In a second step, we describe the standard deviation of unit values within each product
category in the Trade Unit Values and Comtrade databases. The median standard deviation of
unit values by HS 6-digits product code is computed for the year 2007. We also report the
first and third quartiles in order to provide a more accurate picture of trade price dispersion
within product categories.
Figure 2 starts the analysis using the full Comtrade dataset, and Comtrade subsamples relying
on estimated quantities (flag = 4 or 6) and non-estimated quantities (flag = 0 or 2). As
expected, the estimation of quantities in Comtrade dramatically reduces the standard deviation
of unit values within each product category. This is even more the case within product
categories where trade price dispersion is more important (3rd quartile).
19
CEPII, WP No 2011-10
The Trade Unit Values Database
Figure 2. Median standard deviation of the unit values within HS 6-digits product
categories, Comtrade dataset (2007)
Note: The standard deviation of unit values is computed by HS 6-digits product and year using the CIF
unit values with the HS96 revision. Numbers are expressed in US dollars per ton. The top 1% of unit
values was removed within each HS6 product category to drop outliers.
Source: Author’s Calculations
Figure 3 uses both the Comtrade and Trade Unit Values datasets, relying on the same
coverage in terms of observations. The median standard deviation of unit values is found to be
comparable in the Trade Unit Values and Comtrade datasets dataset (around 25 thousand US
dollars per ton in 2007). The difference in terms of price dispersion between the two
databases, however, is more important when we consider product categories with a high
standard deviation of unit values. 25% of product categories have a standard deviation higher
than 84 thousand US dollars in the Trade Unit Values database, against 75 thousand US
dollars in the Comtrade database with a similar coverage (i.e. price dispersion increased by
12% among product categories with higher price differentiation). The Trade Unit Values
dataset therefore offers a higher dispersion of trade prices, in product categories with more
differentiation.
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CEPII, WP No 2011-10
The Trade Unit Values Database
Figure 3. Median standard deviation of the unit values within HS 6-digits product
categories, Trade Unit Values and Comtrade databases with similar coverage (2007)
Note: The standard deviation of unit values is computed by HS 6-digits product and year using the CIF
unit values with the HS96 revision. Numbers are expressed in US dollars per ton. The top 1% of unit
values was removed within each HS6 product category to drop outliers.
Source: Author’s Calculations
4.3. E conometric analysis
In order to assess the reliability of the Trade Unit Values dataset, we estimate the effect of
economic aggregates on unit values from the Trade Unit Values and Comtrade datasets. We
replicate the econometric analysis proposed by Fontagné et al. (2008). CIF unit values are
explained by geographical distance and by the GDP per capita of both source and destination
countries. GDP per capita of both the exporter and importer are traditionally expected to have
a positive influence on trade prices, as well as the geographical distance between the two
countries. Estimation results are provided controlling for product fixed effects. We use both
the Trade Unit Values and Comtrade datasets for the years 2005, 2006 and 2007.
Results in Table 10 show that CIF unit values are positively related to geographical distance
and GDP per capita in all specifications. The R-square is similar in estimations using the
Trade Unit Values and Comtrade datasets (columns 1 and 2). Considering the sample of unit
values that rely on non-estimated quantities in Comtrade (column 3, flag = 0 or 2), and
estimated quantities in Comtrade (column 4, flag = 4 or 6), the R-square is much larger in the
21
CEPII, WP No 2011-10
The Trade Unit Values Database
last column. The reason is that when quantities are estimated in Comtrade, most of the
7
variance is explained by product fixed effects since unit values are mostly product-specific.
Table 10. Relation between CIF unit values and economic aggregates controlling for
product fixed effects (2005-2007)
(1)
Trade Unit Value
(2)
Comtrade
(3)
Comtrade
(flag = 0 or 2)
CIF unit value
0.548
0.534
0.509
0.744
0.080***
(0.006)
0.228***
(0.006)
0.160***
(0.005)
0.056***
(0.006)
0.199***
(0.005)
0.169***
(0.005)
0.071***
(0.006)
0.233***
(0.006)
0.202***
(0.005)
0.008*
(0.005)
0.050***
(0.003)
0.033***
(0.003)
14,039,499
Yes
Yes
16,755,796
Yes
Yes
13,678,977
Yes
Yes
3,062,331
Yes
Yes
Database
Dependent variable
R-squared
ldist
lgdp_cap_i
lgdp_cap_j
Observations
Product fixed effect
Year dummies
(4)
Comtrade
(flag = 4 or 6)
Notes: Coefficients obtained with OLS estimation of the equation. Significance levels: *** at 1%, **
at 5%, * at 10%. Standard errors clustered by country pairs. Estimation includes year dummies.
Differences in the R-squares between the Trade Unit Values dataset and the Comtrade Dataset
in Table 10 can possibly be explained by differences in the composition of observations. In
Table 11, the estimation is performed using the Trade Unit Values database and the Comtrade
database, sharing the same coverage in terms of observations (11.9 million). The first two
columns report estimation results without product fixed effects whereas columns (3) and (4)
use product fixed effects. Finally, columns (5) and (6) report estimation results including
product fixed effects, where the sample relies on non-estimated quantities in Comtrade.
Without product fixed effects, the R-square of estimations relying on the Trade Unit Values
and Comtrade datasets are similar, and share comparable coefficients on GDP per capita and
geographical distance. When product fixed effects are included, however, the R-square of the
estimation using the Comtrade dataset (column 4) appears larger the estimation relying on the
7
This is due to the use of « standard unit values » by product category to estimate missing quantity in Comtrade. In
unreported estimations without product fixed effects, the R-square for estimations relying on Comtrade unit values
with estimated quantity is lower than in alternative subsamples.
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CEPII, WP No 2011-10
The Trade Unit Values Database
Trade Unit Values dataset (column 3). This is explained by the fact that part of the unit values
observations in Comtrade rely on quantities estimated using standard unit values. When we
remove observations where quantity is estimated in Comtrade (columns 5 and 6), the Rsquare remains similar for estimations that rely on the Trade Unit Values and Comtrade
samples.
Overall, these results show that although the dispersion of trade prices is larger in the Trade
Unit Values database, the power of explanation of the empirical model that we estimate, using
bilateral distance and the GDP per capita of both partners as explanatory variables, is not
reduced. This result implies that the larger dispersion in the Trade Unit Values database is
well explained by economic aggregates. This econometric analysis confirms that our
processing improves the reliability of unit values, as a proxy for trade price.
Table 11. Relation between CIF unit values and economic aggregates using the Trade
Unit Values and Comtrade datasets with a similar coverage (2005 – 2007)
Database
Sample
(1)
Trade Unit
Value
(2)
Comtrade
(3)
Trade Unit
Value
Intersection
ldist
lgdp_cap_i
lgdp_cap_j
Comtrade
Intersection
Dependent
variable
R-squared
(4)
(5)
(6)
Trade Unit Comtrade
Value
Intersection, flag = 0 or
2 in Comtrade
CIF unit value
0.060
0.064
0.553
0.622
0.608
0.612
0.197***
(0.008)
0.266***
(0.008)
0.191***
(0.007)
0.192***
(0.007)
0.242***
(0.007)
0.188***
(0.006)
0.069***
(0.007)
0.235***
(0.006)
0.163***
(0.005)
0.068***
(0.006)
0.211***
(0.005)
0.160***
(0.005)
0.076***
(0.006)
0.232***
(0.006)
0.176***
(0.005)
0.077***
(0.006)
0.231***
(0.006)
0.176***
(0.005)
Observations
11,947,093 11,947,093 11,947,093 11,947,093 10,442,510 10,442,510
Product
fixed
effect
No
No
Yes
Yes
Yes
Yes
Year dummies
Yes
Yes
Yes
Yes
Yes
Yes
Notes: Coefficients obtained with OLS estimation of the equation. Significance levels: *** at 1%, ** at 5%, * at
10%. Standard errors clustered by country pairs. Estimation includes year dummies.
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CEPII, WP No 2011-10
The Trade Unit Values Database
C ONC L USI ON
This paper presents the methodology followed to construct the Trade Unit Values database
provided by the CEPII. This database relies on raw data for trade values and quantities at the
highest available level of disaggregation (tariff lines). We believe that our processing strategy
improves the reliability of unit values data for bilateral international trade, as compared to
existing datasets.
Unit values are used by researchers as a proxy for trade prices. Unit values are, however,
subject to a number of statistical biases, due to the aggregation issues and the treatment of
missing quantity information in worldwide trade datasets. Our strategy relies on highly
disaggregated trade data (tariff lines) and improves the aggregation of unit values into HS 6digits product categories. Contrary to existing datasets, most unit values in our dataset do not
rely on the estimation of missing quantity information. We also implement a correction of
outlier unit values. Overall, we improve the dispersion of unit values, for a given product
category, as compared to observations in Comtrade. A simple econometric application shows
that this high dispersion of unit values is well explained by a standard gravity model. Our
strategy therefore improves the reliability of unit values as a proxy for trade prices.
The Trade Unit Values database therefore allows a better comparability of trade prices, in a
given market and for a given year. This new database can therefore improve the empirical
works dedicated to the study of price discrimination across markets, and the specialization of
countries on vertically differentiated varieties.
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CEPII, WP No 2011-10
The Trade Unit Values Database
B I B L I OG R APHY
Paulo Bastos and Joana Silva, 2008, “The Quality of a Firm’s Exports: Where you Export to
Matters,” Discussion Papers 08/18, University of Nottingham, GEP.
Christian Broda & David E. Weinstein, 2006, "Globalization and the Gains from Variety,"
The Quarterly Journal of Economics, MIT Press, vol. 121(2), pages 541-585, May.
José Manuel Campa, Linda S. Goldberg and Jose Manuel González Mìnguez, 2005,
“Exchange Rate Pass-Through to Import Prices in the Euro Area,” CEPR Discussion Papers
5347, C.E.P.R. Discussion Papers.
Lionel Fontagné, Guillaume Gaulier and Soledad Zignago, 2008, “Specialization Across
Varieties and North–South Competition”, Economic Policy, 23 (53): 51-91.
Guillaume Gaulier and Soledad Zignago, 2010 “BACI: International Trade Database at the
Product-level. The 1994-2007 Version”, CEPII Working Paper N. 2010-23.
Holger Görg, László Halpern and Balázs Muraközy, 2010, “Why do within firm-product
export prices differ across markets?,” CEPR Discussion Papers 7708, C.E.P.R. Discussion
Papers.
Amit Khandelwal, 2009, "The Long and Short (of) Quality Ladders," NBER Working Papers
15178.
Kalina Manova and Zhiwei Zhang, 2010, “Export Prices across Firms and Destinations”,
mimeo Stanford University.
Julien Martin, 2009, “Spatial Price Discrimination in International Markets,” Working Papers
2009-21, CEPII research center.
Mathias Reister and Markie Muryawan, 2009, “Quantity and weight data in UN Comtrade”,
UN Comtrade background paper.
Peter K. Schott, 2008. "The relative sophistication of Chinese exports," Economic Policy,
CEPR, CES, MSH, vol. 23, pages 5-49, 01.
United Nations Statistical Division (UNSD), 2009, “Quantity information of UN Comtrade”
UNSD Report, Expert Group on International Merchandise Trade Statistics Second meeting
New York.
Chang Won and Alan L. Winters “How Regional Blocs Affect Excluded Countries: The Price
Effects of MERCOSUR”, The American Economic Review Vol. 92, No. 4 (Sep., 2002), pp.
889-904.
25
CEPII, WP No 2011-10
The Trade Unit Values Database
A PPE NDI X
A 1. C ountry coverage in the T rade Unit V alue database
number
of
years in the
Unit Value
database
number
of
years in the
Unit Value
database
number
of
years in the
Unit Value
database
Afghanistan
1
Germany
9
Panama
4
Albania
9
Ghana
5
Papua New Guinea
1
Algeria
9
Kiribati
2
Paraguay
5
Andorra
5
Greece
9
Peru
4
Antigua and Barbuda
4
Greenland
8
Philippines
9
Azerbaijan
9
Grenada
5
Poland
5
Argentina
9
Guatemala
4
Portugal
4
Australia
5
Guinea
5
Guinea-Bissau
3
Austria
9
Guyana
4
East Timor
2
Bahamas
7
Honduras
6
Qatar
4
Bahrain
7
Hong Kong (SARC)
4
Taiwan, Province
4
Bangladesh
8
Hungary
6
Russian Federation
9
Armenia
9
Iceland
4
Rwanda
5
Barbados
9
Indonesia
7
Saint Kitts and Nevis
9
Belgium
9
Iran (Islamic Republic)
7
Anguilla
8
Bermuda
4
Iraq
3
Saint Lucia
7
Bhutan
2
Ireland
8
Saint Vincent and
7
Bolivia
4
Israel
4
Sao Tome and Principe
9
Bosnia and Herzegovina
6
Italy
9
Saudi Arabia
6
Botswana
7
Côte d'Ivoire
6
Senegal
7
Brazil
9
Jamaica
7
Seychelles
9
Belize
9
Japan
4
India
9
Solomon Islands
6
Kazakstan
9
Singapore
9
Brunei Darussalam
1
Jordan
4
Slovakia
7
Bulgaria
4
Kenya
4
Viet Nam
9
Burundi
7
Korea, Rep. of Korea
8
Slovenia
9
Belarus
9
Kuwait
8
South Africa
7
Cambodia
6
Kyrgyzstan
4
Zimbabwe
4
Cameroon
7
Lebanon
5
Spain
4
Canada
7
Lesotho
2
Sudan
9
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CEPII, WP No 2011-10
The Trade Unit Values Database
Cape Verde
6
Latvia
4
Suriname
9
Central African Republic
2
Lithuania
9
Swaziland
7
Sri Lanka
4
Luxembourg
4
Sweden
7
Chile
9
Macau
4
Switzerland
7
China
9
Madagascar
9
Syrian Arab Republic
4
Colombia
4
Malawi
9
Thailand
9
Comoros
8
Malaysia
5
Togo
7
Mayotte
9
Maldives
7
Tonga
8
Cook Islands
6
Mali
8
Trinidad and Tobago
5
Costa Rica
6
Malta
5
United Arab Emirates
7
Croatia
9
Mauritania
9
Tunisia
9
Cuba
5
Mauritius
4
Turkey
9
Cyprus
9
Mexico
9
Turks and Caicos
4
Czech Republic
9
Mongolia
4
Tuvalu
6
Benin
4
Moldova, Rep.of
8
Uganda
9
Denmark
9
Montserrat
5
Ukraine
6
Dominica
9
Morocco
4
The former Yugoslav
9
Dominican Republic
3
Mozambique
9
Egypt
4
Ecuador
4
Oman
6
United Kingdom
9
El Salvador
9
Namibia
5
Tanzania, United
7
Ethiopia
5
Netherlands
9
United States of
9
Estonia
9
Netherland Antilles
4
Burkina Faso
3
Faroe Islands
8
Aruba
9
Uruguay
9
Fiji
4
New Caledonia
6
Venezuela
5
Finland
4
Vanuatu
2
Wallis and Futuna
7
France
9
New Zealand
4
Samoa
7
French Polynesia
5
Nicaragua
6
Yemen
8
Gabon
2
Niger
9
Yugoslavia
5
Georgia
8
Nigeria
3
Zambia
9
Gambia
5
Norway
7
Occupied Palestinian
9
Pakistan
5
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CEPII, WP No 2011-10
The Trade Unit Values Database
A 2. Summary of the quantity cor rection in C omtrade
Starting in 2005, a new processing system has been implemented by the UN Statistical
8
Division Comtrade with the aim of improving the coverage of quantity information. Quantity
information is estimated when quantity is simply missing, when quantity units do not match
World Customs Organization recommendations, or when extreme values are detected. All the
processing that is presented below is performed using the raw tariff lines data aggregated at
the HS 6-digits level for values and quantities separately.
(i)
Quantity units do not match World Customs Organization recommendations
In order to allow international comparisons and comparisons in a given year, standard practice
requires converting all quantity units into weights, when weights are not initially available.
The UN Statistical Division uses empirical conversion factors provided by the declaring
countries, or eventually by the FAO for agricultural commodities. When conversion factors
are not available, weights are estimated using the procedure detailed below (paragraph iii).
(ii) Detection of extreme quantities
The detection of extreme quantity information relies on unit values, with two criteria. First, a
unit value is identified as an outlier if it exceeds the maximum historical value *10 or is
below the maximum historical value/10. The maximum historical value correspond to the
maximum of the average unit value for a given reporter and product for the last five years.
9
The second detection criteria uses the concept of the “Standard Unit Value”. The Standard
Unit Values is the median unit value of a product, computed at the world level. The unit value
has to lie in a range that is bounded by the standard unit value*2 and the standard unit
value/2.
(iii) Estimation of quantities for extreme and missing weights
When weights information is missing or detected as extreme, the raw quantity (missing or
not) is replaced by an estimated one. Let us label i the reporter country, j the partner country,
k the product, and t the year. A first level of treatment uses, for a given reporter-product-year
(ikt), the average unit value computed from reliable trade flows (Weighted Unit Value). The
trade value of the “suspect” quantity is then combined with this average unit value to estimate
the new quantity. A second level of treatment uses a Standard Unit Value computed at the
World level, for each product k, using information from the previous year. This standard unit
value is simply the median unit value at the World level. In this case the value flow of the
“suspect” quantity is combined with the Standard Unit Value to estimate the new quantity.
Importantly, this second level of treatment is implemented in the case where the first one
fails.
8
See the UN Comtrade companion paper by Reister and Muryawan (2009), and the UNSD Report “Quantity
information of UN Comtrade” in November 2009.
9
See the Annex II of Reister and Muryawan (2009).
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CEPII, WP No 2011-10
The Trade Unit Values Database
This methodology is extremely useful to provide comparable information on quantity across
countries, within detailed product categories. However, it also narrows the heterogeneity of
unit values across countries of the same good category, for two reasons: first, extreme
quantities are detected using the same unit values criteria for all countries. Then, the second
level of treatment for the “suspect” quantities (detailed above) assumes the same unit value
for all “suspect” flows for a given product.
29
CEPII, WP No 2011-10
The Trade Unit Values Database
L I ST
OF W OR K I NG PAPE R S R E L E A SE D B Y
C E PI I
An Exhaustive list is available on the website: \\www.cepii.fr.
No
Title
Authors
2011-09
Carbon Price Drivers: Phase I versus Phase II A. Creti,
P.-A. Jouvet
Equilibrium
& V. Mignon
2011-08
Rebalancing Growth in China:
Perspective
2011-07
Economic Integration in the EuroMed: Current Status J. Jarreau
and Review of Studies
2011-06
The Decision to Import Capital Goods in India: Firms' A. Berthou & M. Bas
Financial Factors Matter
2011-05
FDI from the South: the Role of Institutional Distance M. Aleksynska
and Natural Resources
& O. Havrylchyk
An International A. Bénassy-Quéré,
B. Carton & L. Gauvin
2011-04b What International Monetary System for a fast- A. Bénassy-Quéré
changing World Economy?
& J. Pisani-Ferry
2011-04a Quel système monétaire international pour une A. Bénassy-Quéré
économie mondiale en mutation rapide ?
& J. Pisani-Ferry
2011-03
China’s Foreign Trade in the Perspective of a more G. Gaulier,
Balanced Economic Growth
& D. Ünal
2011-02
The Interactions between the Credit Default Swap and V. Coudert & M. Gex
the Bond Markets in Financial Turmoil
2011-01
Comparative Advantage and Within-Industry Firms M. Crozet & F. Trionfetti
Performance
2010-33
Export Performance and Credit Constraints in China
2010-32
Export Performance of China’s domestic Firms: The F. Mayneris & S. Poncet
Role of Foreign Export Spillovers
30
F. Lemoine
J. Jarreau & S. Poncet
CEPII, WP No 2011-10
The Trade Unit Values Database
No
Title
Authors
2010-31
Wholesalers in International Trade
M. Crozet,
& S. Poncet
2010-30
TVA et taux de marge : une analyse empirique sur P. Andra,
M. Carré
données d’entreprises
& A. Bénassy-Quéré
2010-29
Economic and Cultural Assimilation and Integration M. Aleksynska
of Immigrants in Europe
& Y. Algan
2010-28
Les firmes françaises dans le commerce de service
G. Gaulier,
& D. Mirza
2010-27
The world Economy in 2050: a Tentative Picture
J. Fouré,
A. Bénassy-Quéré
& L. Fontagné
2010-26
Determinants and Pervasiveness of the Evasion of S. Jean
Customs Duties
& C. Mitaritonna
2010-25
On the Link between Credit Procyclicality and Bank V. Bouvatier,
Competition
A. Lopez-Villavicencio
& V. Mignon
2010-24
Are Derivatives Dangerous? A Literature Survey
2010-23
BACI: International Trade Database at the Product- G. Gaulier
Level – The 1994-2007 Version
& Soledad Zignago
2010-22
Indirect Exporters
2010-21
Réformes des retraites en France : évaluation de la X. Chojnicki
mise en place d’un système par comptes notionnels
& R. Magnani
2010-20
The Art of Exceptions: Sensitive Products in the Doha C. Gouel, C. Mitaritonna
Negotiations
& M.P. Ramos
2010-19
Measuring Intangible Capital Investment:
Application to the “French Data”
2010-18
Clustering the Winners: The French Policy of L. Fontagné, P. Koenig,
Competitiveness Clusters
F. Mayneris &S. Poncet
G. Lalanne
E. Milet
G. Capelle-Blancard
F. McCann
31
an V. Delbecque
& L. Nayman
CEPII, WP No 2011-10
The Trade Unit Values Database
No
Title
Authors
2010-17
The Credit Default Swap Market and the Settlement V. Coudert & M. Gex
of Large Defauts
2010-16
The Impact of the 2007-10 Crisis on the Geography G. Capelle-Blancard
of Finance
& Y. Tadjeddine
2010-15
Socially Responsible Investing : It Takes more than G. Capelle-Blancard
Words
& S. Monjon
2010-14
A Case for Intermediate Exchange-Rate Regimes
2010-13
Gold and Financial Assets: Are they any Safe Havens V. Coudert
in Bear Markets?
& H. Raymond
2010-12
European Export Performance
2010-11
The Effects of the Subprime Crisis on the Latin G. Dufrénot, V. Mignon
American Financial Markets:
An Empirical & A. Péguin-Feissolle
Assessment
2010-10
Foreign Bank Presence and its Effect on Firm Entry O. Havrylchyk
and Exit in Transition Economies
2010-09
The Disorted Effect of Financial Development on A. Berthou
International Trade Flows
2010-08
Exchange Rate Flexibility across Financial Crises
2010-07
Crises and the Collapse of World Trade: The Shift to A. Berthou
Lower Quality
C. Emlinger
2010-06
The heterogeneous effect of international outsourcing Fergal McCann
on firm productivity
2010-05
Fiscal Expectations on the Stability and Growth Pact: M. Poplawski-Ribeiro
Evidence from Survey Data
& J.C. Rüle
2010-04
Terrorism Networks and Trade: Does the Neighbor J. de Sousa,
Hurt
& T. Verdier
V. Salins
& A. Bénassy-Quéré
A. Cheptea, L. Fontagné
& S. Zignago
32
V. Coudert, C. Couharde
& V. Mignon
&
D. Mirza
CEPII, WP No 2011-10
The Trade Unit Values Database
No
Title
Authors
2010-03
Wage Bargaining and the Boundaries of the M. Bas & J. Carluccio
Multinational Firm
2010-02
Estimation of Consistent Multi-Country FEERs
2010-01
The Elusive Impact of Investing Abroad for Japanese L. Hering,
Parent Firms: Can Disaggregation According to FDI & S. Poncet
Motives Help
33
B. Carton & K. Hervé
T. Inui